在显示对话框时，我得到“ onSaveInstanceState之后无法执行此操作”

一些用户正在报告，如果他们使用通知栏中的快速操作，则他们将被强制关闭。

我在通知中显示了一个快速操作，该通知调用了“ TestDialog”类。在按下“ snooze”按钮后的TestDialog类中，我将显示SnoozeDialog。

private View.OnClickListener btnSnoozeOnClick() {
    return new View.OnClickListener() {

        public void onClick(View v) {
            showSnoozeDialog();
        }
    };
}

private void showSnoozeDialog() {
    FragmentManager fm = getSupportFragmentManager();
    SnoozeDialog snoozeDialog = new SnoozeDialog();
    snoozeDialog.show(fm, "snooze_dialog");
}

错误是 *IllegalStateException: Can not perform this action after onSaveInstanceState*.

引发IllegarStateException的代码行是：

snoozeDialog.show(fm, "snooze_dialog");

该类扩展了“ FragmentActivity”，而“ SnoozeDialog”类扩展了“ DialogFragment”。

这是错误的完整堆栈跟踪：

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
at android.support.v4.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1327)
at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1338)
at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:574)
at android.support.v4.app.DialogFragment.show(DialogFragment.java:127)
at com.test.testing.TestDialog.f(TestDialog.java:538)
at com.test.testing.TestDialog.e(TestDialog.java:524)
at com.test.testing.TestDialog.d(TestDialog.java:519)
at com.test.testing.g.onClick(TestDialog.java:648)
at android.view.View.performClick(View.java:3620)
at android.view.View$PerformClick.run(View.java:14292)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4507)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
at dalvik.system.NativeStart.main(Native Method)

我无法重现此错误，但是我收到了很多错误报告。

谁能帮我解决这个错误？

这是普遍的问题。我们通过重写show（）和处理DialogFragment扩展类中的异常来解决此问题

public class CustomDialogFragment extends DialogFragment {

    @Override
    public void show(FragmentManager manager, String tag) {
        try {
            FragmentTransaction ft = manager.beginTransaction();
            ft.add(this, tag);
            ft.commit();
        } catch (IllegalStateException e) {
            Log.d("ABSDIALOGFRAG", "Exception", e);
        }
    }
}

请注意，应用此方法不会更改DialogFragment.class的内部字段：

boolean mDismissed;
boolean mShownByMe;

在某些情况下，这可能会导致意外结果。最好使用commitAllowingStateLoss（）而不是commit（）

这意味着您commit()（show()在DialogFragment的情况下）在之后进行分段onSaveInstanceState()。

Android会将您的片段状态保存在onSaveInstanceState()。因此，如果您commit()接连onSaveInstanceState()碎片，碎片状态将丢失。

结果，如果Activity被杀死并在以后重新创建，那么该片段将不会添加到不良用户体验的Activity中。这就是为什么Android不允许不惜一切代价造成状态损失的原因。

简单的解决方案是检查状态是否已经保存。

boolean mIsStateAlreadySaved = false;
boolean mPendingShowDialog = false;

@Override
public void onResumeFragments(){
    super.onResumeFragments();
    mIsStateAlreadySaved = false;
    if(mPendingShowDialog){
        mPendingShowDialog = false;
        showSnoozeDialog();
    }
}

@Override
public void onPause() {
    super.onPause();
    mIsStateAlreadySaved = true;
}

private void showSnoozeDialog() {
    if(mIsStateAlreadySaved){
        mPendingShowDialog = true;
    }else{
        FragmentManager fm = getSupportFragmentManager();
        SnoozeDialog snoozeDialog = new SnoozeDialog();
        snoozeDialog.show(fm, "snooze_dialog");
    }
}

注意：片段恢复时将调用onResumeFragments（）。

private void showSnoozeDialog() {
    FragmentManager fm = getSupportFragmentManager();
    SnoozeDialog snoozeDialog = new SnoozeDialog();
    // snoozeDialog.show(fm, "snooze_dialog");
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.add(snoozeDialog, "snooze_dialog");
    ft.commitAllowingStateLoss();
}

参考：链接

几天后，我想分享我的解决方案如何，我已经修复它，以示DialogFragment你应该重写show()它的方法和调用commitAllowingStateLoss()的Transaction对象。这是Kotlin中的示例：

override fun show(manager: FragmentManager?, tag: String?) {
        try {
            val ft = manager?.beginTransaction()
            ft?.add(this, tag)
            ft?.commitAllowingStateLoss()
        } catch (ignored: IllegalStateException) {

        }

    }

如果对话框不是很重要（可以关闭应用程序/不再显示该视图就可以不显示该对话框），请使用：

boolean running = false;

@Override
public void onStart() {
    running = true;
    super.onStart();
}

@Override
public void onStop() {
    running = false;
    super.onStop();
}

并仅在运行时打开对话框（片段）：

if (running) {
    yourDialog.show(...);
}

编辑，可能更好的解决方案：

在生命周期中调用onSaveInstanceState的位置是不可预测的，我认为更好的解决方案是像这样检查isSavedInstanceStateDone（）：

/**
 * True if SavedInstanceState was done, and activity was not restarted or resumed yet.
 */
private boolean savedInstanceStateDone;

@Override
protected void onResume() {
    super.onResume();

    savedInstanceStateDone = false;
}

@Override
protected void onStart() {
    super.onStart();

    savedInstanceStateDone = false;
}

protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    savedInstanceStateDone = true;
}


/**
 * Returns true if SavedInstanceState was done, and activity was not restarted or resumed yet.
 */
public boolean isSavedInstanceStateDone() {
    return savedInstanceStateDone;
}

我已经遇到这个问题很多年了。
互联网上散布着成百上千（数百？数千？）关于此的讨论，并且其中的困惑和虚假信息似乎很多。
为了使情况变得更糟，本着xkcd“ 14标准”漫画的精神，我将答案投了出去。

在cancelPendingInputEvents()，commitAllowingStateLoss()，catch (IllegalStateException e)，和类似的解决方案都显得残酷。

希望以下内容可以轻松地显示如何重现和解决该问题：

private static final Handler sHandler = new Handler();
private boolean mIsAfterOnSaveInstanceState = true;

@Override
protected void onSaveInstanceState(Bundle outState)
{
    super.onSaveInstanceState(outState);
    mIsAfterOnSaveInstanceState = true; // <- To repro, comment out this line
}

@Override
protected void onPostResume()
{
    super.onPostResume();
    mIsAfterOnSaveInstanceState = false;
}

@Override
protected void onResume()
{
    super.onResume();
    sHandler.removeCallbacks(test);
}

@Override
protected void onPause()
{
    super.onPause();
    sHandler.postDelayed(test, 5000);
}

Runnable test = new Runnable()
{
    @Override
    public void run()
    {
        if (mIsAfterOnSaveInstanceState)
        {
            // TODO: Consider saving state so that during or after onPostResume a dialog can be shown with the latest text
            return;
        }

        FragmentManager fm = getSupportFragmentManager();
        DialogFragment dialogFragment = (DialogFragment) fm.findFragmentByTag("foo");
        if (dialogFragment != null)
        {
            dialogFragment.dismiss();
        }

        dialogFragment = GenericPromptSingleButtonDialogFragment.newInstance("title", "message", "button");
        dialogFragment.show(fm, "foo");

        sHandler.postDelayed(test, 5000);
    }
};

请尝试使用FragmentTransaction而不是FragmentManager。我认为以下代码将解决您的问题。如果没有，请告诉我。

FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
SnoozeDialog snoozeDialog = new SnoozeDialog();
snoozeDialog.show(ft, "snooze_dialog");

编辑：

片段交易

请检查此链接。我认为它将解决您的疑问。

使用Activity-KTX的新生命周期范围，就像以下代码示例一样简单：

lifecycleScope.launchWhenResumed {
   showErrorDialog(...)
}

可以在onStop（）之后直接调用此方法，并且一旦返回就调用onResume（），它将成功显示对话框。

许多视图将高级事件（例如单击处理程序）发布到事件队列中以推迟运行。因此，问题在于已经为Activity调用了“ onSaveInstanceState”，但事件队列包含了延迟的“单击事件”。因此，当此事件分派给您的处理程序时

at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)

并且您的代码会show引发IllegalStateException。

最简单的解决方案是清理事件队列， onSaveInstanceState

protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        // ..... do some work
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            findViewById(android.R.id.content).cancelPendingInputEvents();
        }
}

使您的对话框片段对象成为全局对象，并在onPause（）方法中调用dismissAllowingStateLoss（）

@Override
protected void onPause() {
    super.onPause();

    if (dialogFragment != null) {
        dialogFragment.dismissAllowingStateLoss();
    }
}

不要忘记在片段中分配值，并在单击按钮或任何地方调用show（）。

尽管在任何地方都没有正式提到它，但是我几次遇到了这个问题。以我的经验，兼容性库在较旧平台上支持片段存在问题，这会导致此问题。您可以通过使用常规片段管理器API对此进行测试。如果没有任何效果，则可以使用普通对话框代替对话框片段。

1. 将此类添加到您的项目中：（必须位于android.support.v4.app包中）

包android.support.v4.app;


/ **
 *由Gil于8/16/2017创建。
 * /

公共类StatelessDialogFragment扩展DialogFragment {
    / **
     *显示对话框，使用现有事务添加片段，然后提交
     *交易，同时允许状态损失。

     *
     *我建议您大多数时候都使用{@link #show（FragmentTransaction，String）}，但
     *这是您完全不关心的对话框。（调试/跟踪/广告等）
     *
     * @参数交易
     *在其中添加片段的现有事务。
     * @param标签
     *此片段的标签，按照
     * {@link FragmentTransaction＃add（Fragment，String）FragmentTransaction.add}。
     * @return返回已提交事务的标识符，按照
     * {@link FragmentTransaction＃commit（）FragmentTransaction.commit（）}。
     * @see StatelessDialogFragment＃showAllowingStateLoss（FragmentManager，String）
     * /
    public int showAllowingStateLoss（FragmentTransaction transaction，String tag）
    {
        mDismissed =假；
        mShownByMe = true;
        transaction.add（this，tag）;
        mViewDestroyed = false;
        mBackStackId = transaction.commitAllowingStateLoss（）;
        返回mBackStackId;
    }

    / **
     *显示对话框，将片段添加到给定的FragmentManager中。这很方便
     *用于显式创建事务，并使用给定标签将片段添加到其中，以及
     *提交它而不关心状态。这并没有交易添加到
     *返回堆栈。当片段被消除时，将执行新的事务以将其删除
     *来自活动。

     *
     *我建议您大多数时候都使用{@link #show（FragmentManager，String）}，但这是
     *用于您根本不关心的对话框。（调试/跟踪/广告等）
     *
     *
     * @参数经理
     *该片段将被添加到FragmentManager。
     * @param标签
     *此片段的标签，按照
     * {@link FragmentTransaction＃add（Fragment，String）FragmentTransaction.add}。
     * @see StatelessDialogFragment＃showAllowingStateLoss（FragmentTransaction，String）
     * /
    公共无效的showAllowingStateLoss（FragmentManager管理器，字符串标记）
    {
        mDismissed =假；
        mShownByMe = true;
        FragmentTransaction ft = manager.beginTransaction（）;
        ft.add（this，tag）;
        ft.commitAllowingStateLoss（）;
    }
}

2. 扩展StatelessDialogFragment而不是DialogFragment

3. 使用方法showAllowingStateLoss代替show

4. 请享用 ;）

使用此代码

FragmentTransaction ft = fm.beginTransaction();
        ft.add(yourFragment, "fragment_tag");
        ft.commitAllowingStateLoss();

代替

yourFragment.show(fm, "fragment_tag");

通过使用反射，我已经找到了解决此问题的理想解决方案。上述所有解决方案的问题是，字段mDismissed和mShownByMe不会更改其状态。

只需在您自己的自定义底部工作表对话框片段中覆盖方法“ show”，如下面的示例（Kotlin）

override fun show(manager: FragmentManager, tag: String?) {
        val mDismissedField = DialogFragment::class.java.getDeclaredField("mDismissed")
        mDismissedField.isAccessible = true
        mDismissedField.setBoolean(this, false)

        val mShownByMeField = DialogFragment::class.java.getDeclaredField("mShownByMe")
        mShownByMeField.isAccessible = true
        mShownByMeField.setBoolean(this, true)

        manager.beginTransaction()
                .add(this, tag)
                .commitAllowingStateLoss()
    }

以下实现可用于解决在Activity生命周期中安全地执行状态更改的问题，尤其是用于显示对话框的问题：如果实例状态已经保存（例如由于配置更改），它将推迟状态直到恢复到已恢复状态为止被执行。

public abstract class XAppCompatActivity extends AppCompatActivity {

    private String TAG = this.getClass().getSimpleName();

    /** The retained fragment for this activity */
    private ActivityRetainFragment retainFragment;

    /** If true the instance state has been saved and we are going to die... */
    private boolean instanceStateSaved;

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);

        // get hold of retain Fragment we'll be using
        retainFragment = ActivityRetainFragment.get(this, "Fragment-" + this.getClass().getName());
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();

        // reset instance saved state
        instanceStateSaved = false;

        // execute all the posted tasks
        for (ActivityTask task : retainFragment.tasks) task.exec(this);
        retainFragment.tasks.clear();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        instanceStateSaved = true;
    }

    /**
     * Checks if the activity state has been already saved.
     * After that event we are no longer allowed to commit fragment transactions.
     * @return true if the instance state has been saved
     */
    public boolean isInstanceStateSaved() {
        return instanceStateSaved;
    }

    /**
     * Posts a task to be executed when the activity state has not yet been saved
     * @param task The task to be executed
     * @return true if the task executed immediately, false if it has been queued
     */
    public final boolean post(ActivityTask task)
    {
        // execute it immediately if we have not been saved
        if (!isInstanceStateSaved()) {
            task.exec(this);
            return true;
        }

        // save it for better times
        retainFragment.tasks.add(task);
        return false;
    }

    /** Fragment used to retain activity data among re-instantiations */
    public static class ActivityRetainFragment extends Fragment {

        /**
         * Returns the single instance of this fragment, creating it if necessary
         * @param activity The Activity performing the request
         * @param name The name to be given to the Fragment
         * @return The Fragment
         */
        public static ActivityRetainFragment get(XAppCompatActivity activity, String name) {

            // find the retained fragment on activity restarts
            FragmentManager fm = activity.getSupportFragmentManager();
            ActivityRetainFragment fragment = (ActivityRetainFragment) fm.findFragmentByTag(name);

            // create the fragment and data the first time
            if (fragment == null) {
                // add the fragment
                fragment = new ActivityRetainFragment();
                fm.beginTransaction().add(fragment, name).commit();
            }

            return fragment;
        }

        /** The queued tasks */
        private LinkedList<ActivityTask> tasks = new LinkedList<>();

        @Override
        public void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);

            // retain this fragment
            setRetainInstance(true);
        }

    }

    /** A task which needs to be performed by the activity when it is "fully operational" */
    public interface ActivityTask {

        /**
         * Executed this task on the specified activity
         * @param activity The activity
         */
        void exec(XAppCompatActivity activity);
    }
}

然后使用这样的类：

/** AppCompatDialogFragment implementing additional compatibility checks */
public abstract class XAppCompatDialogFragment extends AppCompatDialogFragment {

    /**
     * Shows this dialog as soon as possible
     * @param activity The activity to which this dialog belongs to
     * @param tag The dialog fragment tag
     * @return true if the dialog has been shown immediately, false if the activity state has been saved
     *         and it is not possible to show it immediately
     */
    public boolean showRequest(XAppCompatActivity activity, final String tag) {
        return showRequest(activity, tag, null);
    }

    /**
     * Shows this dialog as soon as possible
     * @param activity The activity to which this dialog belongs to
     * @param tag The dialog fragment tag
     * @param args The dialog arguments
     * @return true if the dialog has been shown immediately, false if the activity state has been saved
     *         and it is not possible to show it immediately
     */
    public boolean showRequest(XAppCompatActivity activity, final String tag, final Bundle args)
    {
        return activity.post(new XAppCompatActivity.ActivityTask() {
            @Override
            public void exec(XAppCompatActivity activity) {
                if (args!= null) setArguments(args);
                show(activity.getSupportFragmentManager(), tag);
            }
        });
    }

    /**
     * Dismiss this dialog as soon as possible
     * @return true if the dialog has been dismissed immediately, false if the activity state has been saved
     *         and it is not possible to dismissed it immediately
     */
    public boolean dismissRequest()
    {
        return dismissRequest(null);
    }

    /**
     * Dismiss this dialog as soon as possible
     * @param runnable Actions to be performed before dialog dismissal
     * @return true if the dialog has been dismissed immediately, false if the activity state has been saved
     *         and it is not possible to dismissed it immediately
     */
    public boolean dismissRequest(final Runnable runnable)
    {
        // workaround as in rare cases the activity could be null
        XAppCompatActivity activity = (XAppCompatActivity)getActivity();
        if (activity == null) return false;

        // post the dialog dismissal
        return activity.post(new XAppCompatActivity.ActivityTask() {
            @Override
            public void exec(XAppCompatActivity activity) {
                if (runnable != null) runnable.run();
                dismiss();
            }
        });
    }
}

您可以安全地显示对话框，而不必担心应用程序状态：

public class TestDialog extends XAppCompatDialogFragment {

    private final static String TEST_DIALOG = "TEST_DIALOG";

    public static void show(XAppCompatActivity activity) {
        new TestDialog().showRequest(activity, TEST_DIALOG);
    }

    public TestDialog() {}

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState)
    {
        return new AlertDialog.Builder(getActivity(), R.style.DialogFragmentTheme /* or null as you prefer */)
                .setTitle(R.string.title)
                // set all the other parameters you need, e.g. Message, Icon, etc.
                ).create();
    }
}

然后TestDialog.show(this)从您的内部呼叫XAppCompatActivity。

如果要使用参数创建更通用的对话框类，可以将它们Bundle与show()方法中的参数一起保存在中，并使用getArguments()in进行检索onCreateDialog()。

整个方法似乎有点复杂，但是一旦为活动和对话框创建了两个基类，它就很容易使用并且可以正常工作。它可以用于Fragment可能受同一问题影响的其他基于基础的操作。

发生此错误的原因是，在onSaveInstanceState调用之后将传递输入事件（例如按键或onclick事件）。

解决方案是onSaveInstanceState在“活动”中覆盖并取消所有未决事件。

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
        final View rootView = findViewById(android.R.id.content);
        if (rootView != null) {
            rootView.cancelPendingInputEvents();
        }
    }
}